Determination of Pesticides in Carrots by Gas Chromatography–Mass Spectrometry

ABSTRACT

A sensitive and selective method was developed to determine pesticides in carrots by gas chromatography–mass spectrometry following the development of an optimized extraction procedure. The method was validated for 30 organochlorine pesticides for gas chromatography with electron capture detection obtaining limit of detection from 0.18 to 0.92?µg/kg except for cis- and trans-permenthrin. Twenty-six carrot samples were analyzed and six pesticides were detected. The results compared with the accepted maximum residue levels in correlation to crop origin.     

Thin-Film Microextraction Coupled with Mass Spectrometry and Liquid Chromatography–Mass Spectrometry

Thin-film microextraction (TFME) is a format of solid-phase microextraction (SPME) technique which offers improvement of sensitivity without sacrificing time through the increase of available surface area and extractive phase volume. This technique offers significant advantages which make it attractive for many analytical/bioanalytical applications. This review discusses the fundamental principle of TFME and its benefits versus the rod fiber geometry of SPME, and demonstrates the agreements of the experimental data for the available TFME systems with the theoretical concept. The current configurations, coating chemistries, coating preparation methods, and applications for TFME system are reported.     

Scopes of Bioanalytical Chromatography–Mass Spectrometry

Journal of Analytical Chemistry - The areas of application of modern bioanalytical chromatography–mass spectrometry are so extensive that any attempt to systematize them becomes subjective....     

Preliminary Characterization of the Composition and Phenolic Fragmentation of Olive Byproducts by Gas Chromatography–Mass Spectrometry and High-Performance Liquid Chromatography–Tandem Mass Spectrometry

Olive waste is a potential resource due to its rich variety of biologically active compounds. To investigate chemical components of olive waste, the selected samples were extracted using ultrasound assisted enzyme hydrolysis and petroleum ether, ethyl acetate and n-butyl alcohol were used to obtain a series of solvent extracts. Gas chromatography–mass spectrometry analysis showed hydrocarbons, esters, acids, alcohols, and ketones present in the extracts. Some fatty acids were considered to be predominant; it is noteworthy that phenolic compounds were detected in the ethyl acetate extract fraction. Furthermore, the primary phenolic compounds were also determined by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. The possible fragmentation patterns have been proposed in positive and negative ion modes; the main fragment ions were observed from the loss of methyl, hydroxyl, or carboxyl groups. The compounds showed different fragmentation ions types in both positive and negative ionization modes and gave structural information on the main phenolic compounds in olive waste. The results of this study may be used to identify valuable active compounds and guide commercial applications of olive waste.     

Determination of Volatiles in Water Lily Flowers Using Gas Chromatography–Mass Spectrometry

Volatile organic compounds in the stamens, petals, and pistils of 56 water lily cultivars were determined by headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. The stamens released a majority of the volatiles. A total of 117 volatile organic compounds were determined. Alkanes and alkenes were the most abundant, followed by aldehydes and ketones. Cluster analysis was used to divide the cultivars into three subsets characterized by specific aromatic compounds and associated aromas. Discriminant analysis confirmed the results of the cluster analysis. Three tropical water lily cultivars Colorata, 34, and Ai Ji Bai and one hardy water lily cultivar Somptuosa had particularly high aromatic compound concentrations and are recommended to produce fragrant, colorful, and hardy specimens.     

Determination of Four Volatile Compounds with Anti-Inflammatory Biological Activity in Houttuynia chordata Thunb. by Gas Chromatography and Gas Chromatography–Mass Spectrometry

An analytical procedure was developed for the determination of four volatile components with anti-inflammatory biological activity in Houttuynia cordata Thunb. by gas chromatography and gas chromatography–mass spectrometry. Four compounds (α-pinene, β-myrcene, 1-decanol and 2-undecanone) were selected as analytes because they are common major constituents in volatile compositions of Houttuynia cordata Thunb Anti-inflammatory efficacy in vivo suggested that the four compounds provided inhibitory effects on xylene-induced ear edema formation in a dose-dependent manner. The four compounds were determined by gas chromatography in mouse serum after oral administration of volatile oil and water distillate liquid of Houttuynia cordata Thunb Related chromatographic conditions were investigated and selected. A good separation of the four compounds and internal standard was achieved. The method reflected the quality of Houttuynia cordata Thunb. and its preparations.     

Identification of Spillages of Semi-Volatile Hydrocarbon Fuels in Soils by Gas Chromatography–Mass Spectrometry

A possibility of the identification of semi-volatile hydrocarbon fuels in soil samples by studying the distribution of biomarkers of the sesquiterpane class is shown. The extraction of a soil sample with methylene chloride and the subsequent analysis of the extract by gas chromatography–mass spectrometry ensured the detection of these hydrocarbons in RG-1 and T-1 rocket kerosenes, TS-1 aviation kerosene, and diesel fuel. It was found that the distribution of the compounds found is characteristic for each type of fuel and is preserved in their transformations in the soil. The parameters reflecting the distribution of biomarkers and ensuring the identification of the type of fuel at any stage of transformation are proposed.     

Gas Chromatography–Mass Spectrometry Determination of Pregabalin in Human Plasma Using Derivatization Method

A gas chromatography–mass spectrometry method for the determination of pregabalin in human plasma is described. The procedure involves precipitation of protein, liquid–liquid extraction with ethylene glycol monomethyl ether, and derivatization with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide in the presence of N-hydroxysuccinimide as additive. Separation was attained on HP column (30 m × 0. 25 mm ID, 0.25 μm) coupled with mass spectrometric detector using electron impact selected ion monitoring. The assay showed an excellent linearity in the concentration range of 0.36–10 μg mL^?1 with correlation coefficient (r²) values of 0.999. The intra- and inter-day assay variations for three different concentration levels were less than 10%. The limit of quantification was detected at 0.36 μg mL^?1. The method is highly specific, precise, accurate, and reproducible and could also be applied for the determination of pregabalin in human plasma.     

Determination of n-Alkanes in Jet Fuel by Cold-electron Ionization Gas Chromatography–Mass Spectrometry

A rapid, easy, and reliable method was developed for the characterization of jet fuel with minimal sample preparation. A standard solution of 13 aliphatic n-alkanes in hexane was used to evaluate and validate the separation using cold-electron ionization gas chromatography–mass spectrometry. The method was evaluated and validated by the linearity, accuracy, and precision for all analytes. The limits of detection and quantification for each n-alkane were also evaluated. Nine major n-alkanes from n-octane to n-hexadecane were positively identified and quantified in jet fuel due to the enhanced molecular ion in the mass spectra. Major n-alkanes and their corresponding isomers in jet fuel were also identified from the extracted ion chromatograms. n-Undecane, n-dodecane, n-tridecane, and n-tetradecane were present at the highest concentrations in jet fuel at approximately 7% (v/v). The total concentrations of total straight chain alkanes were 34–37% in jet fuel that was comparable with the standard value of 32%.     

Quantification of Cannabinoids in Cultivars of Cannabis sp. by Gas Chromatography–Mass Spectrometry

Chromatographia - In the chemical characterization of medically valued Cannabis, the present work has used a gas chromatography (GC) method coupled with mass spectrometry (MS) for identification...     

Determination of Aromatic Microbial Metabolites in Blood Serum by Gas Chromatography–Mass Spectrometry

We present the results of the determination of eight aromatic microbial metabolites, phenylcarboxylic acids (PhCAs), by gas chromatography–mass spectrometry after their liquid–liquid extraction from serum samples and derivatization. The analytical range for the analytes is 0.5–40 μM. The concentration of phenylcarboxylic acids in the serum of healthy donors (n = 40) and the time profile of the concentration of different PhCAs in serum samples of four patients from the intensive care unit (ICU) are studied. The results correlated with the severity of the clinical state of patients.     

Determination of Herbicides in Corn Flour by Novel Extraction and Gas Chromatography–Mass Spectrometry

A simple and efficient procedure was developed to determine eight herbicides in corn flour by gas chromatography–mass spectrometry in selected ion-monitoring mode. Samples were prepared with a modified, quick, easy, rapid, effective, rugged, and safe procedure. The type and volume of extraction solvent, type and amount of adsorbent, and time of sonication were optimized. The protocol method was rigorously verified. The mean recoveries were from 85 to 108% at various fortification levels with relative standard deviations below 15% and limits of quantification from 4 to 48?ng g^?1. The method was used to determine herbicides in corn flour.     

Novel Sampling for the Determination of Naphthalene in Air by Gas Chromatography–Mass Spectrometry

Here are reported two new sampling method approaches for the determination of naphthalene in ambient air for concentrations from 0.25 to 18.7?µg/L. The first method used for gas phase naphthalene analysis produced an average recovery of 88.8% and the second method using headspace sampling produced an average recovery of 93.8%. The second method showed better recovery than the former, so it was used for subsequent comparative gas-phase determination of naphthalene. The second method was validated at various naphthalene concentrations and humidity using a naphthalene gas generator to produce various naphthalene standards and a naphthalene-monitoring instrument. The naphthalene concentrations generated using the gas generator and determined second sampling method with gas chromatography–mass spectrometry (GC–MS) were compared to the sensor measurements and were in good agreement. In summary, the sampling methods presented provided reliable gas-phase naphthalene determination when coupled with GC–MS.     

Optimized Ultrasonic Extraction for the Determination of Polyaromatic Hydrocarbons by Gas Chromatography–Mass Spectrometry

The presence of polycyclic aromatic hydrocarbons (PAHs) in soil is an issue of concern due to their harmful effects on human health. The goal of this study was to optimize ultrasonic extraction to establish an efficient, easy, and low-cost method for the determination of 16 priority PAHs in soil. The time of extraction and solvent systems were optimized with the analysis by gas chromatography–mass spectrometry. The method was validated, and the optimum results were obtained using 1:1 cyclohexane:acetone and 1:1 hexane:acetone solvent systems with 30- and 60-min sonication times.     

Radiation-Chemical Purification of Water from Petroleum Products as Studied by Gas Chromatography–Mass Spectrometry

The radiation-chemical purification of water from petroleum products (diesel oil, motor oil, and residual fuel oil) was studied by gas chromatography–mass spectrometry. The removal of -radiolysis products with molecular weights from 40 to 500 amu was examined. Organic compounds (toluene, ethylbenzene, xylenes, other alkylbenzenes, C₁₄–C₁₈ n-alkanes, naphthalene, methylnaphthalenes, and tetralin) were virtually completely removed at a dose of 25 kGy. An interpretation of the data was presented.     

Determination of δ-Hexadecanesultone in Anionic Surfactants and Detergents by Gas Chromatography–Mass Spectrometry

Journal of Analytical Chemistry - A method is proposed for the determination of sultones in the anionic surfactant sodium α-olefin sulfonate (AOS Na) and products based on this surfactant. The...     

Application of Gas Chromatography and Gas Chromatography–Mass Spectrometry to the Detection of γ-Hydroxybutyric Acid and Its Precursors in Various Materials

Modified procedures were developed for the detection of -hydroxybutyric acid and 1,4-butanediol (its metabolic precursor) in foods, food additives, and urine using gas chromatography and gas chromatography–mass spectrometry. The analytical range was 0.1–20 wt %.     

Determination of α-Tocopherol in Olive Oil by Solid-Phase Microextraction and Gas Chromatography–Mass Spectrometry

Olive oil has great human health benefits and is an important component of the Mediterranean diet. Its quality, sensory attributes, and oxidative stability are linked to the presence of minor compounds. Vitamin E (α-tocopherol) is a key component in these properties. In this work, solid-phase microextraction coupled to gas chromatography–mass spectrometry was used for the determination of α-tocopherol in olive oil. The analytical performance of the method has been assessed in fortified olive oil with negligible vitamin E concentrations. The calibration curve was linear from 0.020 to 0.500?mg/g. The limits of detection and quantification were 0.006 and 0.021?mg/g, respectively. Intraday and interday relative standard deviations were 3.2 and 10.0, respectively, and were concentration independent. The method was used for the determination of α-tocopherol in virgin and extra virgin olive oil, reporting average concentrations of 0.044?±?0.03 and 0.200?±?0.05?mg/g, respectively. Overall, the method is simple, sensitive, rapid, and solvent free, and provided high recoveries of 97.7?±?3.1%. In addition, vitamin E stability in extra-virgin olive oil was characterized by a shelf-life study.     

Determination of Toluene and Ethanol in Urine by Headspace and Cryotrapping Gas Chromatography–Mass Spectrometry

Toluene is the major volatile organic compound found in glue and is often used as a hallucinogenic for abusers. Use with alcohol increases the risk of adverse effects from toluene exposure. In this study, a headspace and cryotrapping gas chromatography–mass spectrometry method was developed and validated for the determination of toluene and ethanol in urine. Experimental and instrumental variables were investigated to optimize the method for sensitivity. Excess sodium sulfate was used as the salting-out reagent before the headspace protocol. Linear least squares regression with a 1/x weighting factor was used to construct calibration curves from 0.002 to 0.4?µg?mL^?1 for toluene and 10 to 2000?µg?mL^?1 for ethanol. The correlation coefficients exceeded 0.9993. The limits of detection were 0.0005?µg?mL^?1 for toluene and 0.21?µg?mL^?1 for ethanol. Intraday and interday precisions were within 5.4 and 11.5%, while intraday and interday accuracies were between ?11.3 to ?4.0% and ?11.0 to 1.2%, respectively. The method validation results for selectivity and stability were satisfactory. The validation results were used to estimate the expanded uncertainty and the contribution of individual steps in the method for the quantification of toluene and ethanol. The relative expanded uncertainties were 14.1% for toluene and 4.6% for ethanol.     

Metabonomic Analysis of Urine from Chronic Unpredictable Mild Stress Rats Using Gas Chromatography–Mass Spectrometry

Depression is a prevalent complex psychiatric disorder and its pathophysiological mechanism is not yet well understood. In this study, we investigated the metabolic profiling of urine samples from chronic unpredictable mild stress (CUMS) rats to find potential disease biomarkers and research pathology of depression. Metabolome in urine was analyzed using gas chromatography/mass spectrometry (GC/MS) in conjunction with multivariate statistical techniques. The urine samples of male Sprague–Dawley rats were collected at different time points and then were derivatized by methoximation/silylation. Clear separation between the model and control group was achieved, and 15 metabolites were identified, which suggested that the depressed state may be related to neurotransmitter, energy metabolism and immunity. The time-dependent trajectory of metabolites pattern revealed that the maximum biochemical change happened on the 21st day, which was consistent with the results of behavior tests. The study suggested that the metabonomic approach could be used as a potentially powerful tool to investigate the biochemical change in certain physiopathological conditions, such as depression, as an early diagnostic means.